Various forms of inhaler are already known, and among these are the ones in which the capsule is pierced, usually at the ends, in order to allow the medicament to be withdrawn during inhalation, and those in which the cap portion of the capsule is removed from the body portion in order to allow the medicament to be extracted.
Extraction of the medicament usually occurs as a result of the inhaled airstream passing over or through the capsule.
With both of the above types of inhaler, it is known to allow the airstream passing through the inhaler to adopt a vortical configuration which results in the pierced capsule or the separated capsule cap and body portions tumbling in the airstream.
It is a disadvantage of virtually all of the known inhalers that not all of the medicament is withdrawn from the capsule or the separated capsule cap and body portions, and this is frequently because the capsule portions or the capsule as a whole can become lodged in the inhaler in a position where either the extraction effect of the inhalation air is unable to operate effectively or the capsule or capsule cap and body portions can become prevented from tumbling freely by a mechanical constraint.